The present invention relates to a device for stirring molten metal in a continuous casting operation in which the molten metal flows in a controlled manner from a reservoir, via a spout, to an ingot mold. More particularly, this invention relates to a molten metal stirring device including at least one electromagnetic inductor comprising a magnetic core and windings and designed to induce a rotational movement in the molten metal.
A device of the type hereinabove described is known from document EP-A No. 0,093,068. Electromagnetic stirring, as disclosed in EP-A No. 0,093,068 has been successfully used. The main advantages of electromagnetic stirring are that not only can the spouts be cleaned should they become clogged up; but also, it is possible to prevent slag and inclusions floating on the surface of the metal bath from being sucked in by the whirlpools which form during continuous casting. This is particularly true when the electromagnetic stirring device is applied inside the ingot mold or immediately below the ingot mold. In order to monitor correct cleaning of the spouts, an inductor operating system is used which is connected both to the system controlling the rate at which the ingot mold is fed with liquid metal and to the system monitoring the level of the metal inside the ingot mold. Thus, when this metal level falls (which is automatically compensated for by an increase in the feed rate), and when it is noticed that this compensating operation can be performed only with difficulty, it is possible to conclude that the spout has become clogged.
The document GB-A No. 2,024,679 corresponding to U.S. Pat. No. 4,256,165 describes another stirring device comprising one or more electromagnetic inductors which are mounted on movable crossbeams and which can be retracted when it is advantageous to perform casting without stirring. However, this device does not have the efficiency and output of the powerful single-core inductor described in EP-A No. 0,093,068 (which surrounds the molten metal and is capable of inducing a rotational field in the metal).
The document GB-A No. 2,006,068 disclosed a multipolar inductor which comprises several poles extending perpendicularly from a single core and which allows a casting line to be approached on one side only, despite the presence of feed rollers which, in the operating position, are located between the poles of the inductor. However, this inductor can only exert a unilateral effect because it does not allow the casting line to be accessed through 360.degree..